The present invention relates generally to steering systems for vehicles, and more particularly to a steer-by-wire system with a fail-safe function, which electrically controls an operating section and a steered section mechanically separated with each other and includes a clutch mechanism for mechanically connecting the operating section and the steered section as a backup system.
Recent years, there have been disclosed various steer-by-wire systems for automotive vehicles, with which the feedback torque applied to the steering wheel and the steer angle of the steerable wheels can be arbitrarily determined. In general, a steer-by-wire system includes a mechanical backup system in a column shaft connecting a steering wheel and a steering mechanism for ensuring safety in the event of a system failure. However, with a shaft such as a column shaft for a mechanical backup system, flexibility in layout design of a cockpit, which is an advantage of steer-by-wire systems, is not sufficiently provided. In lieu thereof, a steer-by-wire system utilizing a cable mechanism as a mechanical backup system, with which a comparably higher flexibility in layout design of a cockpit is provided, is proposed. One such steer-by-wire system is disclosed in Japanese Patent Provisional Publication No. 2002-225733 published Aug. 14, 2002 (hereinafter is referred to as “JP2002-225733”).